Use a laptop computer; they use 90% less energy than desktop computers.
Check furnace air filters monthly and change or clean periodically. A clean filter saves 5% on heating costs.
Now is the time to clean and repair your fireplace. Make sure that the damper is tightly sealed when the fireplace is not in use. A small space would let the cold air rush in and send the warm air out.
Check for cracks and gaps between door and window frames, around your dryer vent, and where cable and phone lines enter your home. Most air leaks can be easily sealed with caulk or weather stripping.
Consider installing motion sensors on porch lights. This saves energy because lights will automatically turn on and off.
Vacuuming and wiping clean light bulbs and lighting fixtures can also help save energy. Dust and kitchen grease can build up and reduce the bulbs’ brightness, requiring you to turn on more fixtures to get the light you need.
If you have single-pane windows, add storm windows to cut heat loss by up to 50%. Fall is the best time to remove the window air conditioners for the winter. If they must stay in place, be sure to seal them with caulking or tape and cover them with an airtight, insulated jacket.
Fall is the best time to clean the chimney and have your vent systems checked. Pipes must be properly connected and there should be no signs of rust or damage.